Method of producing impregnants



Patented July 28, 1942 ldETHOD F PRODUCING IMPREGNANTS Jaoquelin E. Harvey, In, Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga.,a corporation of Georgia 'No Drawing. Application July 13, 1940, Serial No. 345,440

1 Claim.

The present invention relates to a production of useful impregnants. More especially, the present invention relates to the production of wood preserving impregnants from high boiling hydrocarbons containing molecular complexes, and has as an object the carrying on of hydrogenation in such a manner as to exercise a control of the characteristics of the finished product.

It is a further object of the present invention to provide a process for hydrogenation of high boiling fractions of tars of aromatic content, in-

cluding pitch, topped tar and residual tar in such a manner as to finally convert substantially the entirety into satisfactory substitutes for specification wood preserving impregnants.

Wood preserving impregnants currently onthe market have varied boiling ranges and other characteristics, said characteristics generally being determined by proposed usage.

Wood preserving oils, for the most part, may be divided in three major classifications, viz., various creosote-coal tar solution types, various creosotes, and wood preserving oils lighter than creosote, as for example the wood preserving wood shingle stain oils.

Among the current starting materials for the recovery of wood preserving distillates is coal tar which because of its availability is a preferred starting material.

At present, in the order of 500-800 million gallons of coal tar are produced annually in this country. The annual average consumption of tar derived wood preserving oils is in the order of 200 million gallons. If the aforenamed production of coal tar were processed to produce creosote or the like including creosote-coal tar solution oil the resulting amount of creosote, etc. would be in the order of 200 million gallons. Thus, this country could be self-sufficient in its creosote or wood preserving oil requirements. However, this is not economically feasible or possible for the reason that when coal tar is distilled to yield a wood preserving distillate, there is also produced a residual mass (pitch) which meets with great sales resistance. Generally, this pitch represents from 50 to 75% of the overall tar. Because of the limited market for pitch in this country the coal tar distiller must confine the amount of creosote he produces to the corresponding amount of pitch that he can sell at a profit. Thus, from this situation obtaining stems the necessity of yearly importing in the order of from 50 to 100 million gallons of tar derived wood preserving oils.

The present invention provides a method for converting larger percentages of tars of aromatic contents, or fraction thereof, into acceptable Wood preserving impregnants, and at times approaches volume for volume conversion. The present invention constitutes an improvementon Patent No. 2,082,885 issued to me on June 8, 1937. The process described in said patent provided a method for converting coal tar or the like, into acceptable wood preserving oils, wherein conversion approached unit, and at times, even greater volumetric percentages. Said method provided a process for first distilling creosote from said tar, and then subjecting the pitch to controlled hydrogenation for conversion of said pitch into wood preserving oils of induced toxicity, said induced toxicity flowing from the controlled action of hydrogen.

I have found that When'practicing a process as described in my former patent, that is to say, when subjecting the starting feed to a temperature of 300500 0., that the induction of toxicity is enhanced by specific provision of'means for decomposition of oxygenated compounds, that is to say, toxicity induction is enhanced when specific and added means are provided tending to influence decomposition of oxygenated compounds contained in the starting material.

Thus, the present invention provides a process for the hydrogenation of coal tar residuals, or the like, into oils of the Wood preserving type having induced toxicity with the added provision of enhancing said toxicity-induction by decomposition of the oxygenated compounds contained therein, as hereinafter described.

The following examples will show various modes of practicing the present invention, wherein toxicity induction is enhanced by added specific means.

Example 1.-A coal tar, specific gravity 1.12, and substantially above 10% coke residue is distilled to an upper limit of 355 C. whereby to recover natural creosote. The resultant pitch was then charged to an autoclave designed to withstand high pressure and high temperature and subjected to a temperature of from 300-500 C. and a hydrogen pressure of from 20-500 atmospheres while, as is usual with such process, keeping the contents of the autoclave agitated. The catalyst was molybdenum sulfide with added tin chloride. Hydrogenation was continued under named conditions until test samples withdrawn showed that fractions had been induced falling within the range of a wood preserving distillate, that is to say, as an example, any of the wood residual tar. 300 atmospheres.

not more than not more than 25% not more than 1% not more than not less than 65% not more than 1 Up to 300 0., not more than 16 A Up to 355 C., not less than 45% 4. A. W. P. A.:

a. Up to 210 C., 1). Up to 235 C.,

5. A. W. P. A.:

a. Up to 210 C., 1). Up to 235 0.,

6. A. W. P. A.:

a. Up to 210 C., b. Up to 235 C.,

7. Prussian Ry.:

a. Up to 210 0., not more than 3% 5. Up to 200 0., not more than 10% 0. Up to 235 C., not more than 25% 8. N. P. V. & L. A. #220:

a. 5% at 162 C. b. 97% at 270 C.

9. S. P. S. S. 0.!

a. 5% at 137 C. b. 95% at 250 C.

10. N. S. S. 0.!

a. I. B. P., 150 C. b. 5% at 205 C. c. 95% at 292 C.

11. Carbolineums:

a. I. B. P., 270 C.

In the example shown it was elected to induce a low boiling end so that when a distillate was recovered from said beneficiated material that not more than 5% of said distillate would distill at 210 C. After said low end had been induced in the beneficiated pitch, said beneficiated pitch was then distilled to an upper limit of 355 C. with the distillate serving as a substitute for grade I creosote, and having toxic properties induced by the controlled action of hydrogen and the decomposition of oxygenated compounds as influenced by halogen derivatives.

Example 2.-A residual tar having an initial boiling point of substantially 250 C. was passed through a high pressure reaction vessel at 400 C. while flowing therewith hydrogen in the amount of 18,000 cubic feet per barrel said Time of reaction 1 hour. Pressure Dissolved gas was removed from the beneficiated residual tar which was then distilled to an upper limit of 300 C. whereby to provide a distillate of enhanced toxicity, suitable as a substitute for a wood preservative shown in the foregoing specifications. Said toxicity induction flowing from reduction of specific gravity, coke residue, viscosity, boiling range, and decomposition of oxygenated compounds.

Example 3.-This process is also specially adapted to the treating of high residue oils, as

not more than 8% not more than 35% not more than 10% not more than 40% not more than 5% not more than for instance those high residue oils recovered from direct recovery stills, or stills wherein tar is distilled to substantial dryness to recover high residue creosotes. The direct recovery still may be set so as to recover all possible volatile matter with the resultant vapors being sent to a fractionating column wherein grade 1 creosote is thrown into one channel and non-permissible oil is thrown into another channel, the non-permissible oil being subjected to the action of hydrogen in the presence of a catalytic material which comprised a material selected from the group consisting of halogens, halids and/or derivatives thereof; temperature, 400 0., pressure 300 atmospheres. Time of treatment 1 hour. The processed material had an initial boiling point, of substantially C. The beneficiated material was distilled to recover a wood preservative as a distillate, said distillate having low boiling ends that conformed to one of the several wood preserving specifications currently acceptable; the process is adapted to produce boiling ranges that may be acceptable in the light of future specifications or, the entire high residue may be so treated that lowered coke residue, specific gravity, viscosity and boiling range provide a substitute for conventional creosote-coal tar solutions when the beneficiated material is used in the entirety. In lieu of treating the high residue as described, the high residue oil may be distilled in a batch still for a recovery of grade one creosote, with the residue therefrom subjected to batch control hydrogenation for the induction of an oil acceptable to the trade because of physical qualities and enhanced toxic value.

In some cases where the starting materials of the present process are relatively high in carbon content, it may be desired to use a comminuted catalyst, with incorporation therein or therewith, or as added material, ofacid or acids, halogen or halogens, halid or halids, derivatives or combinations thereof. For the purpose of influencing decomposition of oxygenated compounds, halid, halids, halogen, halogens, derivative or combinations thereof may be used without addition of other catalytic material.

All catalysts efiective in the presence of hydrogen for the stated purposes areusable. As for instance, chromium, molybdenum, vanadium, uranium, cobalt, copper and their compounds, for instance sulphides or oxides. Promoted or not; with or without small amounts of alkali, acid or halid, or derivatives thereof. Small amounts of halogen or halogens, as such, or incorporated with other substance; eifective catalysts deposited on carriers, as for instance gels, earths, carbon, or the like. Various shapes, as for instance forms, extruded shapes or lengths, pellets, comminuted may be used. Such shapes may be mixed with other materials possessing desired action or not; used with or without other material effecting splitting or not; or with catalyst with added halogen derivatives.

Starting materials of the present process comprise high boiling fractions of tars of aromatic content, as for instance, coal tar, gas house tar, low temperature tar, water gas tar, blast furnace tar, lignite tar, pine tar, wood tar, rosin oil, rosin pitch, high boiling aromatic extracts of petroleum, tars of aromatic content produced by thermal and/or catalytic processing of petroleum or fractions thereof, including gas or gases.

By the term beneficiation as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen under the controls of the present process.

Pressures in the order of 200 atmospheres or higher are preferred; however, lower pressures are usable and will produce the products of the present invention. Those pressures are preferred which provide economic recoveries of the newly formed products. Temperatures of 300 C. and above are preferred although lower temperatures are usable; but when using said lowered temperatures the time element is at times extended to an undue length. Thus, the preferred temperatures are those temperatures which produce economic recoveries of the newly formed product, and are generally selected from the range above 300 C. The time element cannot be expressed a an arbitrary period because of the character of the various starting materials. Periods of from /2 hour or above have shown an increment of the desired products. The time element is so chosen, that when coordinated with the selected temperature and pressure economic recoveries of the newly formed wood preservative of enhanced toxic value is eifected.

The hydrogen of the present process is conveniently supplied by the decomposition of methane. However, hydrogen from whatever source obtained may be used; or materials capable of generating hydrogen may be added whereby to effect the desired hydrogen supply.

Suitable starting materials also include the refined or partially refined high boiling fractions as noted in the foregoing, which statement includes high boiling fractions and pitches, at least once refined by the action of hydrogen.

Example 4.A high boiling tar fraction, initial boiling point substantially 300 C. and end point substantially 400 C. was passed through a high pressure reaction vessel while simultaneously flowing therewith 12,000 cubic feet hydrogen per barrel feed. Pressure 400 atmospheres, catalyst tin sulfide with an iodine derivative. Temperature 420 C. and period of treatment 45 minutes. At the end of said period the beneficiated material was distilled to an upper limit of 270 C. whereby to provide a substitute for N. P. V. & L. A. #220 creosote. The newly formed material had induced toxicity flowing from the controlled action of hydrogen and said catalyst, wherein among other things, oxygenated compounds were decomposed, and boiling range, viscosity and specific gravity reduced.

Thus, it will be seen that the present invention broadly includes the process which converts high boiling tar fractions by the controlled action of hydrogen to substitutes for currently accepted tar derived wood preserving oils, the conversion being characterized by the coordination of time,

temperature and pressure which produces an increment of the desired oil when catalyzed, at least, by a catalyst that influences decomposition of oxygenated compounds.

By the phrase an increment of the desired oil is meant an oil of the tar-derived wood preserving type, which as is well known cannot be produced if the aromatic nuclei of the starting material is ruptured with subsequent degradation, for such procedure would result in production of materials having a deficiency of aromaticity and consequently a deficiency of toxicity.

Example 5.-A high boiling coal tar fraction, initial boiling point substantially 230 C. and end point substantially 420 C. was subjected to the action of hydrogen at 400 C., pressure 300 atmospheres while contacting catalytic material that included cobalt sulfide and tin chloride. Time of contact 1 hour. The processed material because of its boiling range, coke residue, specific gravity, enhanced toxicity, and viscosity provided an acceptable substitute for a creosote derived from tar.

In processes such as in the foregoing examples when a, wood preserving distillate is recovered from the beneficiated starting material, the residue from said distillation may be recycled to the end that conversions from in the order of and upwards may be effected.

The term coal tar in this country means high temperature coal tar.

Minor changes may be made without departing from the spirit of the present invention.

I claim:

In the production of wood preserving impregnants, the process which comprises: subjecting a mixture of high temperature coal tar fractions to the action of a fiow of hydrogen between about 12,000-18,000 cubic feet per barrel material treated Whilst contacting as catalytic materials molybdenum sulfide and tin chloride; maintaining a temperature of at least 400 C. whilst coordinating therewith a pressure of above 200 atmospheres; carrying on the process for such a length of time as to provide a beneficiated material having induced toxic properties, said time being so selected as to provide a beneficiated material which if distilled up to a temperature to provide a distillate as an oil of the wood preserving type said oil of the wood preserving type will distill not more than about 10% at 210 C. and not less than about 45% at 355 C.; and distilling the treated material to provide a distillate as an oil of the wood preserving type having not more than about 10% distilling at 210 C. and not less than about 45% distilling at 355 C.

JACQUELIN E. HARVEY, JR. 

